1. Field of the Invention
The present invention relates to a two-end driven lamp controlling device and, in particular, to a two-end driven lamp controlling device for balancing the brightness of a liquid crystal display (LCD) backlight.
2. Descriptions of the Related Art
Refer to FIG. 1, which is a block diagram of a conventional two-end driven lamp controlling device. As shown, the conventional two-end driven lamp controlling device 1 has a DC power supply 12 disposed on one side of a plurality of lamps 11, the DC power supply 12 is used for supplying DC power to a square wave switch 13, the square wave switch 13 is used for receiving synchronous control signals input from a square wave controller 14 and providing starting transformers 15 with square wave signals and the starting transformers 15 is used for outputting signals such as to drive the lamps 11 in coordination with a plurality of capacitive elements 16, so that the purpose for maintaining a homogenized brightness of the lamps 11 can be fulfilled. According to the block diagram shown in FIG. 1, there should be capacitors disposed at both ends of the lamp, for providing the lamp with sufficiently high voltage to keep the brightness from being inhomogeneous. However, the use of high voltage may cause a problem of voltage endurance, which would be hard to solve, and the use of too many capacitors may increase the cost largely so that a limited application would be present.
Refer to FIG. 2, which is a block diagram of another conventional two-end driven lamp controlling device. As shown, the conventional two-end driven lamp controlling device 1 has a DC power supply 12 disposed on one side of a plurality of lamps 11, the DC power supply 12 is used for supplying DC power to a square wave switch 13, the square wave switch 13 is used for receiving synchronous control signals input from a square wave controller 14 and providing starting transformers 15 numerously corresponding to the lamps 11 with square wave signals and the starting transformers 15 are used for outputting signals such as to drive the lamps 11, so that the purpose for maintaining a homogenized brightness of the lamps 11 can be fulfilled. According to the block diagram shown in FIG. 2, there are starting transformers disposed at both ends of the lamp, which may keep the brightness from being inhomogeneous and solve the problem of voltage endurance. However, the use of so many starting transformers may increase the cost, so that a limited application would be present, also.
Therefore, the above-mentioned conventional techniques have still various shortcomings and, as it being not ideally designed, an improvement is in need. In view of this, the present inventor(s) has (have) set about the work of improvement and innovation and successfully developed the two-end driven lamp controlling device of the present invention through a long-term study and practice.